Classically, a rotor, for example of a low or high pressure turbine, comprises a disk, a series of radial blades mounted in axial housings called cavities made at the periphery of the disk, and a series of platforms that forms an annular stream inside which the gas passing through the turbine circulates.
The blades, and particularly turbine blades are traditionally made of a single metal casting. Fabrication of blades by casting can result in good dimensional tolerances, but on the other hand metal blades have a major disadvantage, namely their high mass.
It has been suggested that blades could be made from a ceramic matrix composite (CMC) material, to overcome this mass problem and with the general purpose of reducing mass in a turbine engine rotor. However, the fabrication of such blades made of CMC is relatively complex and is not well controlled, particularly for the production of blade roots and at platforms.
Thus historically, it has been proposed to make blade platforms separately and assemble them later on the disk, to facilitate fabrication of these blades. Thus, different attachment systems have been developed for platform inserts in disks.
For example, document EP1306523 discloses a rotor with a disk provided with cavities in which blades and platforms are fixed.
Document FR2608674 discloses an alternative to that described in the previous document. The document describes a rotor for a turbine engine comprising a disk in which primary cavities are formed inside which composite ceramic blade roots are inserted axially, and provided with secondary cavities in which bulbs are inserted axially forming means of attachment of platform inserts in the disk. However, in the configuration described in this document, gases can infiltrate between the platforms and the disk, particularly in the cavities of the disk, which has the effect of deteriorating the disk. Furthermore, the proposed geometry complicates assembly/disassembly.
Despite the advantages of platform inserts known in the state of the art that also facilitate assembly and disassembly of the rotor, no solution has been put forward to significantly reduce stresses in the disk of a rotor comprising a plurality of metal blades.